This invention relates to a document handling system for copiers in which the documents may be recirculated for pre-collation copying of both sides of the documents while positively retained in a document transport belt system.
The present invention is an improvement in the pre-collation copying system of U.S. Pat. No. 4,008,956, issued Feb. 22, 1977, to the present applicant, D. J. Stemmle. A similar disclosure is provided in U.S. Pat. No. 3,963,345, issued June 15, 1976, to the same D. J. Stemmle together with M. Silverberg.
These above-cited patents disclose a system for the multiple recirculation of a plurality of individual pre-separated documents in pre-collated order while the documents are continuously retained in a web/scroll system during and between document recirculations. Since that basic web/scroll pre-collation document handling system is utilized herein these patents are incorporated by reference herein. Also incorporated by reference is application Ser. No. 701,371, filed June 30, 1976, now U.S. Pat. No. 4,050,816, issued Sept. 27, 1977 by the same D. J. Stemmle disclosing a similar and related system in which the document is held between two webs. Various art on pre-collation copying systems and on web document transport systems for copying is cited and discussed in these patents and that application and need not be reiterated here.
As taught in the above-cited patents, automatic document recirculation for pre-collation copying with positive, continuous, single system document retention minimizes undesirable document handling, especially transfers between different document transport systems. It is highly desirable for the protection of the documents and the improvement in overall copying effectiveness. This system maximizes document protection by providing continuous support and retention of the documents at alltimes on a document supporting web with no significant slippage between the documents and the web. Further, the web provides an appropriate optical background for the document being copied with minimal background print-out on copies. The present system retains these advantages yet provides the further advantage of unobstructed automatic copying of both sides of the documents.
Exemplary embodiments of the present invention are shown and described hereinbelow incorporated into an otherwise conventional exemplary xerographic apparatus and process. However, it is not limited thereto. The xerographic apparatus and process itself need not be described herein since various patents and known apparatus are available to teach details thereof to those skilled in the art, including those cited above. The present document handling system may be utilized with various known copier optics systems and processing systems. It may be utilized with either a duplex/simplex or duplex/duplex system or mode of operation and in various duplex systems, as will be further discussed herein.
The term "duplex copying" may cover several different copying modes. In duplex/duplex copying, both sides of a document sheet are copied onto both sides of a single copy sheet. In duplex/simplex copying, both sides of a document with images on both sides are copied onto only one side of two successive copy sheets. In simplex/duplex copying, one side of two successive documents (or two page images from microfilm, computer generated output, or the like) are placed on opposite sides of a copy sheet.
The duplex copying of the copy sheets may be done by feeding a set of finished simplexed copy sheets (copy sheets printed only on their first side) through the copying processor for a second pass printing of the second document side image on the opposite side of that copy sheet. Such systems may be referred to as sequential or dual pass duplexing systems. Examples of such systems are shown in U.S. Pat. No. 3,615,219, issued Oct. 26, 1971, to W. A. Drawe, et al., and No. 3,645,615, issued Feb. 29, 1972, to M. R. Spear, Jr., for example.
Alternatively, a single pass or simultaneous duplex system may be used in which unfused images are transferred to both sides of the copy sheet in a single pass, simultaneously or in immediate sequence. Examples of such single pass duplex systems are disclosed, for example, in U.S. Pat. No. 3,697,171, issued Oct. 10, 1972, to W. A. Sullivan, and No. 3,847,478, issued Nov. 12, 1974, to E. F. Young, and the art cited therein.
In the printing industry as opposed to the copy industry, two-sided copying may be referred to as "backing-up".
The present invention is directed to duplex copying systems in which the image sources are a set of original document sheets with images on both sides thereof, in which these duplex documents are automatically recirculated with automatic exposure of both sides of the documents so as to provide either duplex/duplex or duplex/simplex pre-collation copying. It may be utilized with either. In the duplex/duplex mode it may be utilized with either dual pass or single pass copy duplexing systems as described above.
Considering now the art, it may be seen that of particular interest to the present application is art cited below relating to systems providing copying of the images on both sides of document sheets. U.S. Pat. No. 3,862,802, issued Jan. 28, 1975, to H. R. Till discloses a system in which the documents are transported upon a web, wound into a scroll with that web and then ejected from the web in reverse orientation to provide for copying of the second side of a set of documents. However, automatic document recirculation with positive document retention is not provided.
In U.S. Pat. No. 3,844,654, issued Oct. 29, 1974, to J. Guenther, a duplex copying system is disclosed with a document belt for moving documents over a first exposure station and then onto and from a document drum which provides a second exposure station for the opposite sides of the documents.
Patents on apparatus for photographing both sides of documents in which the documents are transported on belts during copying include U.S. Pat. No. 2,194,808, issued Mar. 26, 1940, to F. D. Pooley, Jr., and 3,079,839, issued Mar. 5, 1963, to E. E. Lohner, et al..
Other examples of patents disclosing apparatus for copying both sides of documents includes U.S. Pat. No. 3,227,444, issued Jan. 4, 1966, to J. F. Egan; No. 3,288,464, issued Nov. 29, 1966, to R. W. Thompson; No. 3,318,212, issued May 9, 1967, to D. Rubin; No. 3,408,140, issued Oct. 29, 1968, to K. W. Hemphill; No. 3,506,347, issued Apr. 14, 1970, to C. F. Carlson; No. 3,536,398, issued Oct. 27, 1970, to G. C. Bhagat; No. 3,561,865, issued Feb. 9, 1971, to L. L. Burdick, Jr.; No. 3,672,765, issued June 27, 1972, to C. Altmann; No. 3,936,171, issued Feb. 3, 1976, to E. R. Brooke; and No. 3,947,270, issued Mar. 30, 1976, to A. J. North.